To comprehensively understand the community structure of zooplankton in the epipelagic Eastern Indian Ocean (EIO) and the effects of environmental factors on their distribution, we conducted a survey of zooplankton community structure in the Eastern Indian Ocean (EIO, 12°S-14°N, 80°E-93°E) from March to May 2022. A total of 427 species of adult zooplankton and 24 taxa of zooplankton larvae were microscopically detected from 28 samples. The species accumulation curve indicates that the current sample size is close to adequately capturing most of the species diversity present in the study area. The zooplankton abundance in EIO ranged from 136.8 to 1326.4 ind./m³, with copepods (68.3%) and appendicularia (10.9%) being the main contributors. According to the cluster and multidimensional scaling analyses, the EIO zooplankton community can be divided into 3 distinct ecological groups. Although there was no significant difference in the abundance of the three groups, there was a difference in the distribution of diversity. The highest diversity of species in Group A indicated that zooplankton ecosystems were most stable in the EIO near Sri Lanka. Aggregated boosted tree (ABT) and Generalized Additive models (GAM) suggested that dissolved oxygen, temperature and Chlorophyll a were significant parameters of zooplankton abundance in EIO. Even though the surveyed areas were located in the tropics, Although the surveyed areas are located in the tropics, small temperature differences can also have an impact on the EIO zooplankton.

Zooplankton,Eastern Indian Ocean,Diversity,Environmental parameters